A lumens test rates the total amount of light emitted from a flashlight in all directions. In the most basic sense, a lumen rating measures the amount of light emitted by a source on the inside of a sphere.

The lifespan of the flashlight's battery is the unit of inspection for battery life. The flashlight's brightness after a certain amount of time has passed, or the "Discharge Time," is best depicted graphically.

The IPX rating system is used to quantify water resistance:

• IPX1 — Protects against water falling vertically
• IPX2 — Protects against water falling vertically with component tilted up to 15 deg.
• IPX3 — Protects against water falling vertically with component tilted up to 60 deg
• IPX4 — Protects against water splashing from all directions
• IPX5 — Protects against jets of water with little water permitted
• IPX6 — Protects against heavy seas of water projected with powerful jets
• IPX7 — For up to 30 minutes, submerged in water up to 1 meter deep.
• IPX8 — Up to 30 minutes submerged in water up to 2 meters deep.

The flashlight is left inside a chamber that can simulate varying temperatures for an extended period to observe any ill effects. The temperature outside must not rise above 48 degrees Celsius.

That's how many milliampere-hours the flashlight has, according to the battery test.

For both single units and production runs, you'll need to be able to press the button with lightning speed and efficiency. The critical life testing machine is programmed to press buttons at various speeds to ensure reliable results.